Associations of abdominal discomfort and length of clinical signs with surgical procedure in 181 cases of canine small intestinal foreign body obstruction

Abstract Background Gastrointestinal foreign bodies are a common indication for abdominal exploratory surgery. Objectives The objective of this study was to evaluate the relationship of pre‐operative abdominal discomfort and duration of clinical signs with surgical resolution of canine small intestinal foreign body obstructions (SIFBO). Methods We performed a retrospective study of 181 canine abdominal exploratory surgeries for confirmed SIFBO at two referral hospitals. Animals were categorized into five surgical groups (gastrotomy after manipulation into the stomach, enterotomy, resection‐and‐anastomosis [R&A], manipulated into colon, already in colon) and further grouped by whether entry into the gastrointestinal tract (GIT) was required. Results Abdominal discomfort was noted in 107/181 cases (59.1%), but no significant differences in abdominal discomfort rates were present among the surgical groups or between GIT entry and no entry groups. Clinical sign duration was associated with surgical procedure; median durations were R&A = 3 days (range, 1–9), enterotomy = 2 days (range, 1–14), gastrotomy = 2 days (range, 1–6), already in colon = 1.5 days (range, 1–2), and manipulated into colon = 1 day (range, 1–7). In a pairwise comparison, differences in the duration of clinical signs were found for obstructions manipulated into the colon versus R&A, gastrotomy versus R&A, and in colon versus R&A. When patients were grouped according to GIT entry, cases with entry had a longer duration of clinical signs (median = 2 days [range, 1–14] versus 1 day [range, 1–7], respectively). Conclusions Abdominal discomfort was not associated with surgical complexity; however, the duration of clinical signs was associated with surgical complexity, with longer duration being associated with entry into the GIT and R&A. Despite statistical significance, the maximum difference of 2 days between surgical groups is unlikely to be clinically relevant.

significance, the maximum difference of 2 days between surgical groups is unlikely to be clinically relevant.

K E Y W O R D S emergency surgery, enterotomy, gastrointestinal surgery, gastrotomy INTRODUCTION
Gastrointestinal foreign body obstructions (FBO) are considered by veterinarians to be one of the three most common causes for canine abdominal visceral pain. 1 Clinical signs of abdominal discomfort may include gait or posture changes, physiologic changes such as hyporexia and vomiting, a tense or reactive abdomen on palpation, and changes in behaviour such as lethargy (Beal, 2005;Catanzaro et al., 2016;Wiese, 2015). These clinical manifestations of pain are often non-specific, and a complete diagnostic work-up is required to identify its source. Gastrointestinal FBO often present with similar clinical signs, which vary with the duration, location, and extent of the obstruction (Aronson et al., 2000).
In the case of an FBO, pain arising from the gastrointestinal system may be the result of activation of free nerve endings (A-δ and C-polymodal fibre nociceptors) in the gastrointestinal wall via mechanical stretching of the intestines by the foreign body, ischemia from decreased blood flow, periods of high myoelectric activity, and inflammatory mediators secondary to gastroenteritis or necrosis (Beal, 2005;Ellison, 2010;Mazzaferro, 2003).
Abdominal discomfort has been documented to be a common clinical finding of FBO in dogs with an acute abdomen (Aronson et al., 2000;Beal, 2005;Böhmer et al., 1990;Ellison, 2010;Koike et al., 1981), and, in the authors' personal experience, many veterinary clinicians anecdotally consider the majority of FBO to be painful. However, Hobday et al. (2014) concluded that only 44% of gastrointestinal FBO were painful, with 38% of non-linear FBO and 55% of linear FBO exhibiting signs of abdominal discomfort. Capak et al. (2001) claimed that most cases of gastrointestinal FBO at their hospital over an 18-year period had painful abdomens, but the authors did not report a specific percentage.
The average duration of clinical signs prior to diagnosis of an FBO has been reported to be 4-6 days (Böhmer et al., 1990;Capak et al., 2001;Hayes, 2009;Koike et al., 1981). Variability in time to presentation can be influenced by the degree of obstruction, the severity of clinical signs, and an owner's sense of urgency. An association between longer duration of clinical signs and increased mortality has previously been reported (Hayes, 2009).
To avoid intestinal perforation, prolonged electrolyte and acid-base imbalances, or bacterial translocation, emergency surgical removal is indicated (Aronson et al., 2000;Boag et al., 2005;Ellison, 2010;Papazoglou & Rallis, 2003). Depending on the obstruction location and subsequent bowel health, possible surgical procedures include enterotomy, intestinal resection-and-anastomosis (R&A), gastrotomy after manipulation of the foreign material into the stomach, or manipulation of the material into the colon for future defecation or rectal retrieval. These procedures vary in their complexity as well as overall success and financial cost. Enterotomies typically have a complication rate of 2% (Strelchik et al., 2019). R&A, a more technically challenging procedure, has a reported dehiscence rate of 13%-16% for handsutured closures and 5%-11% for stapled closures (Depompeo et al., 2018;Duell et al., 2016). Gastrotomy, generally considered the preferred surgery when an incision into the gastrointestinal tract (GIT) is required, does not have a published dehiscence rate. Gastrotomy dehiscence is only listed in surgical textbooks as uncommonly occurring (Slatter, 2003). The low dehiscence rate is likely secondary to a robust blood supply promoting healing, ample tissue layers allowing for two-layer closure, and low intraluminal pressures (Boscan et al., 2014;Johnston & Tobias, 2018). In specialty practices, there can be a significant price difference between these procedures.
Our study sought to retrospectively evaluate the potential relationships of abdominal discomfort and duration of clinical signs (prior to presentation) with the surgical procedure required to resolve canine SIFBO. Five surgical treatment groups were considered: gastrotomy after manipulation into the stomach, enterotomy, R&A, manipulated into colon, and already in the colon at the time of surgery. Secondary objectives were to assess if surgical entry into the GIT (gastrotomy, enterotomy, or R&A) was associated with the presence of abdominal discomfort on physical examination or the duration of clinical signs prior to presentation, to compare groups that required surgical entry into the GIT according to whether or not resection of a portion of the intestine was required (gastrotomy/enterotomy versus R&A), and to compare groups that required gastric versus intestinal procedures (gastrotomy versus enterotomy/R&A).
We hypothesized that dogs with obstructions necessitating intestinal R&A would have higher rates of abdominal discomfort and longer durations of clinical signs than dogs with foreign bodies that could be manipulated into the colon or into the stomach for gastrotomy.
Similarly, we hypothesized that dogs with SIFBO requiring enterotomy would have an increased frequency of abdominal discomfort and longer duration of clinical signs, though less so than those with SIFBO requiring R&A.

METHODS
The medical record databases of two private practice specialty hospitals were retrospectively searched to identify dogs that had undergone exploratory laparotomy for a SIFBO confirmed via diagnostic imaging in a 1-year period from April 2019 to April 2020. Cases with incomplete physical examinations or surgical reports were excluded.

Animals
Over the 1-year period, 186 dogs from the two institutions satisfied the inclusion criteria. Five dogs were excluded due to an incomplete medial record (n = 3) or concurrent severe acute abdominal pathology (n = 3), with one patient having both incomplete records and concurrent pathology.

Medical history and physical examination
At the time of initial physical examination at the two referral hospitals, the dogs had a mean body weight of 24.4 kg (range, 2.3-64) ( Table 1).

Group comparisons
When patients were then grouped by procedure (enterotomy, gastrotomy, in colon, manipulated into colon, R&A), there were no statistically significant differences among the groups with respect to age (p = 0.39;  Figure 1), or any other clinical signs (Table 3).
The duration of clinical signs prior to presentation was significantly different among procedures (p = 0.0065; Table 4). Multiple pairwise comparisons revealed that the duration was significantly longer for R&A (median = 3 days) compared with manipulated into colon (median = 1 day), gastrotomy (median = 2 days), and in colon (median 1.5 days), p < 0.05 for each comparison.
When patients were then grouped according to whether they required surgical entry into their GIT (gastrotomy, enterotomy, or R&A) versus not required (manipulated into the colon or in the colon), there were no significant differences in regard to the presence of abdominal discomfort (p = 0.64, Table 5); however, there was a significant difference for the number of days that clinical signs were present prior to presentation (median = 2 and 1, respectively, p = 0.0083) (Figure 2).
For the patients that required surgical entry into their GIT without R&A and those that required R&A, there were no significant differences in regard to the presence of abdominal discomfort (p = 0.24); however, there was a significant difference for the number of days that clinical signs were present prior to presentation (median = 2 and 3, respectively, p = 0.0076) (Table 5, Figure 3).
For the patients that were grouped according to whether they had gastrotomy versus intestinal surgery (enterotomy and R&A), there were no significant differences in regard to the presence of abdominal discomfort (p > 0.99) or the number of days that clinical signs were present prior to presentation (median = 2 and 2, respectively, p = 0.28) (Table 5, Figure 4).

F I G U R E 1
Presence of abdominal discomfort. Standard error bars reported as 95% confidence interval.  (Hayes, 2009;Davis et al., 2017;Gill et al., 2019;Ralphs et al., 2003); however, the presence of abdominal discomfort and the duration of clinical signs have not been previously studied in relationship to the surgical procedure required for resolution of SIFBO. anchor and termination was beyond the scope of this study. Maxwell et al. (2021) previously examined the effect of delayed surgical treatment on the outcomes of gastrointestinal FBO and determined that outcome did not differ; however, a higher likelihood of R&A, increased duration of surgery, longer hospitalization, and later return to eating were all associated with delayed surgical intervention. While the exact timing from hospital admission to surgical procedure was unable to be ascertained from the medical records of all cases, and was therefore beyond the scope of our study, the duration of clinical signs Note: Pairwise multiple comparisons using a Hochberg step-up procedure indicated that the number of days that clinical signs were present prior to presentation was statistically significantly greater for the R&A group compared to Manipulated into colon, in colon, and gastrotomy groups, p < 0.05. Abbreviations: CI, confidence interval; R&A, resection-and-anastomosis. p < 0.05 = significant.

TA B L E 5 Comparisons of combined groups
prior to surgery was similarly associated with a higher rate of entry into the GIT. Additionally, a longer course of clinical signs was noted in R&A cases when compared to those manipulated into the stomach for gastrotomy, manipulated into the colon, and in colon groups. However, given that the range in mean duration of clinical signs was only 2 days between groups, this difference is unlikely to be clinically relevant. While potentially useful to set owner expectations, these findings should not be used in deciding whether to pursue surgery. While all cases in our study survived to the time of discharge, Hayes (2009) reported that a longer timespan from initiation of clinical signs to surgical intervention was associated with increased mortality. As a result, a detailed history, with particular attention to the duration of clinical signs, should be obtained from the owner in cases of suspected SIFBO.
In our study, the mean duration of clinical signs was 2.7 days, a shorter timeframe than the previously reported 4-6 days for gastrointestinal foreign bodies (Böhmer et al., 1990;Capak et al., 2001;Hayes, 2009;Koike et al., 1981 (Catanzaro et al., 2016;Weber et al., 2012). Each published pain score also has limitations and can be considered inefficient or unrealistic in certain clinical settings (Hansen, 2003;Sharkey, 2013). However, generalized abdominal discomfort is routinely noted on physical examination of patients experiencing gastrointestinal upset, as in our study population (Beal, 2005;Catanzaro et al., 2016;Wiese, 2015). Finally, the determination of intestinal tissue viability prior to resection and anastomosis was not standardized between the multiple surgeons, and some surgeons may have performed a R&A when others would have performed an enterotomy. Recommended evaluation of intestinal viability includes intestinal colouration, presence of pulses, and continued peristalsis (Ellison, 2010). Selection bias may have been present due to the incompleteness of the medical record or improper classification of cases in the electronic medical record.
In conclusion, abdominal discomfort is not a significant indicator of associated surgical complexity and risk; however, the duration of clinical signs is an additional preoperative factor to consider in canine SIFBO cases along with the previously recommended factors of cardiovascular stability, serum lactate, electrolyte and acid/base imbalances, septic peritonitis, and overall anaesthetic risk. Additional studies using a verified pain scale and further standardization of intestinal viability parameters are needed to evaluate the relationship between abdominal discomfort and the degree of surgical intervention required.

ACKNOWLEDGEMENT
The authors would like to thank Ethos Discovery for their devotion to developing innovative medical treatments and tests that benefit both humans and animals (www.ethosdiscovery.org). No results or partial results have been presented at a scientific meeting.

SD Stewart and KJ Fryer are employed by Ethos Veterinary Health. AC
Schoelkopf is a former employee of Ethos Veterinary Health.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.

ETHICS STATEMENT
All legal and ethical requirements have been met with regards to the humane treatment of animals in this study.